1. Field of the Invention
The present invention relates to a disk apparatus which drives a head supporting carriage by a voice coil motor.
2. Prior Art
A magnetic hard disk drive apparatus drives a head supporting carriage by a voice coil motor (VCM) to meet a demand of high speed writing and reading. The voice coil motor has a coil connected to the carriage, and a magnet which supplies magnetic flux to the coil. The carriage moves as a current flows through the coil. The coil and magnet are included in an enclosure surrounding a magnetic disk, a head, and the carriage, as shown in FIG.6 and FIG.9 of Japanese Published Unexamined Patent Application No.59-45662.
The surface of the magnet of the voice coil motor is magnetic so that minute particles such as dust etc. stick easily. Also, magnetized particles stick easily to the magnetic disk and magnetic head, and when those particles stuck to the disk peel off, the information recorded on the disk may be destroyed.
U.S. Pat. No. 4,700,246 discloses that a disk and a head are isolated from the magnet by providing an enclosure solely for a voice coil motor, which is separate from an enclosure surrounding the disk and head, to isolate the magnet from the coil of the voice coil motor. The enclosure solely for the voice coil motor is comprised of a cylindrical sleeve with a fringe, a collar with cylindrical projection, a VCM housing cap, and a VCM housing cap seal.
U.S. Pat. No. 4,700,246 requires that many independent parts such as the cylindrical sleeve with a fringe are provided separately to insulate the disk and head from the VCM magnet.
Further, the aforementioned technique disclosed in U.S. Pat. No. 4,700,246 for isolating the disk and head from the VCM magnet is not applicable to a head actuator using what is called rotary VCM which a head supporting carriage is pivotally supported with respect to a predetermined point and current flowing through the coil causes the carriage to pivot with respect to the predetermined point.